Efficient native biosorbent derived from agricultural waste precursor for anionic dye adsorption in synthetic wastewater

Abstract

In this work, a potential biosorbent is prepared from agricultural waste material (ash seed) without any treatment. This biomaterial could be successfully used as a low-cost adsorbent for the removal of an anionic dye named Cibacron Blue (CB), under optimal conditions. The prepared adsorbent was characterized by scanning electron microscope (SEM) coupled with EDX, Fourier transforms infrared spectrometer (FTIR), thermogravimetric analysis (TGA), and point of zero charge (pHpzc). The adsorption experiments were carried out in batch mode at room temperature. Results show that the rate of CB dye removal exceeds 95 % using a dose of 2 g/L ash seed at C0 = 25 mg/L and pH = 2.2. The kinetic data were analyzed using the pseudo-first-order, pseudo-second-order, Elovich’s, Bangham, intraparticle diffusion, and Boyd kinetic. Results show that the pseudo-second-order model fits better the experimental data. The isotherm data of the CB dye adsorption were analyzed with several theoretical models (Langmuir, Freundlich, and monolayer model coupled to real gaz (MMRG)). It was found that the adsorption process of the CB dye is well described by monolayer model coupled to real gaz (MMRG) compared to other models. The negative enthalpy (ΔH°) and free enthalpy (ΔG°) indicate the physical and spontaneous nature of CB adsorption. Therefore, the prepared material can serve as a potential adsorbent for removal of CB dye from industrial effluents.